A pressing device of this type is known, for example, from U.S. Pat. No. 3,662,450. An advantage of this known pressing device is that the individual press members can be moved centrally toward the longitudinal axis of the workpieces which are to be joined. However, this known pressing device is complex in that the individual press members each have to be actuated individually by hydraulic means.
Furthermore, reference is to be made, in connection with the prior art, to U.S. Pat. No. 2,211,008. An advantage of this known pressing device, which has three pressing jaws connected to one another to form a pressing chain, is that the pressing force is applied in a mechanically simple way, by a lever transmission. However, in this case too there is still a significant circumferential component in the movement of the press members during the pressing operation.